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june 28 , 1914
June 28 - Archduke Franz Ferdinand, heir to Austria-Hungary's throne, and his wife, Sophie, are assassinated by Serbian nationalist Gavrilo Princip while the couple were visiting Sarajevo. -
july 28 , 1914
July 28 - Austria-Hungary declares war on Serbia. -
August 1 , 1914
August 1 - Germany declares war on Russia. -
August 3 , 1914
Germany declares war on France. -
august 4 , 1914
The United Kingdom declares war on Germany, after Germany invades Belgium. -
february 4 , 1915
Germany declares a "war zone" around Great Britain, essentially effecting a submarine blockade where even neutral merchant vessels were to be potential targets. -
february 19 , 1915
The Dardanelles Campaign begins. -
April 22 , 1915
The Second Battle of Ypres begins. It is during this battle that the Germans first use poison gas. -
april 25 , 1915
The Battle of Gallipoli begins. -
may 7 ,1915
The British ocean liner RMS Lusitania is sunk by German U-boat, U-20
